Story tips from the Department of Energy’s Oak Ridge National Laboratory, January 2017

Hundreds of tables and plots from papers published about superconductivity are the focus of a Journal of Physics: Condensed Matter review paper that condenses this data into a single graph. "We were able to find a pattern throughout many scientists' work that was never recognized because no one had taken the time to assemble all of the data," said co-author Lance Konzen. He and ORNL's Athena Safa Sefat conclude that superconducting properties of iron- and copper-based materials are highly dependent on the behavior of atomic arrangements inside the unit cells. They noted that their paper, titled "Lattice Parameters Guide Superconductivity in Iron-Arsenides," is a resource that will guide materials chemists and could save considerable time. Konzen's work was sponsored by the Department of Energy's Workforce Development for Teachers and Scientists and the Science Undergraduate Laboratory Internship programs. [Contact: Ron Walli, (865) 576-0226; [email protected]]

Cutline: Atomic arrangements inside the unit cell of an iron-based superconducting material show that reduction of unit cells along the c-axis is necessary for causing superconductivity.

ENVIRONMENT – Triple benefit …

Strategic thinning of forests in the Pacific Northwest and other parts of the United States plagued by fires could produce benefits on multiple levels, according to Rebecca Novello, a researcher at Oak Ridge National Laboratory. In a collaboration with Pacific Northwest National Laboratory and the Forest Service, Novello and Yetta Jager are developing decision support tools for thinning forest understory that could provide biomass for energy, decrease the incidence of high-intensity wildfires and preserve habitat for threatened and endangered salmon. "Climate change is a big driver of this research," Jager said. "Among many other factors, increasing temperatures have shifted seasonal patterns of flow from those that salmon have adapted to and increased the number and duration of wildfires." The three-year project began Oct. 1. [Contact: Ron Walli, (865) 576-0226; [email protected]]

Cutline: Habitats of salmon could be preserved through the careful management of forests.

COMPUTING – Charting new territory …

From machine learning to neuromorphic architectures that enable greater computing flexibility and utility, Oak Ridge National Laboratory researchers are pushing boundaries with Titan. "We're using deep learning to advance the state of the art in several challenging fields such as computer vision and speech recognition," said Steven Young, a member of ORNL's Intelligent Computing Research Team. Young noted that their approach is providing a promising tool in areas previously unexplored by computer scientists. For example, optimal networks for commercial datasets are vastly different than the optimal networks for scientific data. But by utilizing the 18,688 GPUs on Titan and an evolutionary algorithm, researchers can quickly find the best network for their problem. As a result, scientists are seeing and making sense of data that was previously either obscured or simply unavailable for analysis. [Contact: Ron Walli, (865) 576-0226; [email protected]]

Researchers at Oak Ridge National Laboratory found a simpler way to measure adhesion between graphene sheets, compared to a sophisticated method used in a 2015 study: They measured how much graphene deflects when neon atoms poke it from below to create "bubbles." Each bubble's curvature encodes properties such as sheet flexibility and adhesion. "We discovered a new method to measure adhesion of layered materials at very small length scales," said Petro Maksymovych. "It's a simple way to probe a large number of two-dimensional materials and ask how their mechanical properties vary with modifications. It also opens an avenue for atomic-scale control over 2D materials without defects, which may prove useful to achieve their full potential in future technologies." Stacking atomically thin materials opens a pathway toward new energy and electronic applications. [Contact: Dawn Levy, (865) 576-6448; [email protected]]

Cutline: Neon atoms between graphene sheets poke the top sheet from below and stretch the crystalline lattice, forming a bubble at a pressure larger than that of the ocean at its greatest depth. The ORNL method can introduce large local strains into 2D lattices in cases where conventional methods fail.

SUPERCOMPUTING – Resolving the bottleneck …

Scientists at Oak Ridge National Laboratory have proposed a novel cryogenic, or low-temperature, memory cell circuit design that may resolve a memory storage bottleneck, accelerating the pathway to exascale and quantum computing. The proposed design converges write, read and reset memory operations on the same circuit, enabling memory processing functions to operate faster and more efficiently. This could yield decreased access energies and access times and allow for more circuits to occupy less space. Details of the research were published in Superconductor Science and Technology and Physical Review E. [Contact: Sara Shoemaker, (865) 576-9219; [email protected]]